1. Field of the Invention
The present invention relates to a self-adjusting printed circuit board support for use at a printed circuit board screen printing station. More particularly, the present invention relates to a self-adjusting printed circuit board support for use at a screen printer station in a printed circuit board assembly line.
2. Description of Related Art
A common step used during the assembly of active and passive devices onto a printed circuit board is a screen printer station. Typically at this station the circuit is already on the printed circuit board and solder is squeegeed through a screen or template onto the circuit in preparation for subsequent stations where active and passive components are placed on the board. In addition, a screen printer may be used as well to place the circuit pattern on the printed circuit board. Prior art tooling or supports used for holding the printed circuit board in the screen printer station are generally designed for the narrowest printed circuit board, thus leaving large areas of larger printed circuit boards unsupported. Other known support devices require the use of multiple fixed supports which are each designed for a specific width of the various sized printed circuit boards to be assembled.
A universal printed circuit board support which can fully support various sizes of printed circuit board in a screen printer and in the fabrication and/or assembly environments is desirable, and is provided by the present invention.
In one aspect on the invention a printed circuit board support comprises a first member having a planar upper surface for supporting a printed circuit board. At least one second member is movably coupled to a first side of the first member and movable toward and away from the side of the movable member; and a bias source biases the second member in a direction away from the first member.
In another aspect, the present invention provides a printed circuit board support for use at a printed circuit board assembly station which is width-wise adjustable to support printed circuit boards of various width-wise dimensions.
The support comprises a pair of parallel outer rails, each of which has outer surfaces for abutting engagement with one of a pair of spaced surfaces on a positioning device at the assembly station. A pair of parallel inner rails are provided between and spaced from the pair of outer rails, and a mid-block is provided between and spaced from the pair of inner rails. The mid-block and inner and outer rails have upper surfaces for supporting the printed circuit board at the assembly station. A first plurality of rods, each of which is fixed at one end thereof to the first one of the outer rails, extend through a first respective plurality of transverse holes in a first one of the inner rails. A second plurality of rods, each fixed at one end thereof to a second one of the outer rails, extend through a second respective plurality of transverse holes in a second one of the inner rails. A plurality of components for biasing each one of the outer rails and the inner rails outwardly from the mid-block are associated with the rods. The outer rails are moveable toward each other against the bias of the plurality of biasing components by compressive forces applied against the outer rails to fit the outer rails in abutting engagement with the spaced surfaces on the positioning device.
The self adjusting printed circuit board support of the present invention provides maximum support for a wide variety of sizes of printed circuit boards used, for example, in the production of memory modules. When used in a typical screen printer the self-adjusting printed circuit board support of the present invention supports in its length-wise direction the entire length of a printed circuit board. When compressed width-wise, it self adjusts to support the entire width of the printed circuit board.
The support of the present invention is readily compressed by hand to allow placement into or onto a positioning device between a space defined by surfaces of the positioning device and the support expands upon its release to fill the space. When the support is left in the assembly station during a change over to a different width circuit board, the support will automatically adjust to the width fixed by any width-wise adjustment in the space between the surfaces of the positioning device.
The above and other features and advantages of the invention will be more readily understood from the following detailed description which is provided in conjunction with the accompanying drawings.